I've loved making surface changes to my 715T, it seems to take changes better then most other balls. At 1k Saair it has worked great for heavy tourney shots, and bumping it up to 4k saair for my THS it carried the world.
715T drilled 45 x 4 x 35 P4
505T drilled 65 x 3 x 35 P2.5
My 505T is usually 3 to 4 feet later then my 715T, but I can play larger angles with it. 715T is more archy and 505T is sharper for me, but then that's how I've had them drilled.
My experience is that the 715T has a heavier roll then the 505T, but when my 715T starts burning up I can switch to my 505T and continue with that.